1. Field of the Invention
The present invention relates to apatite slurry and a method of manufacture therefor. In particular relates to an apatite slurry which comprises apatite particles which are dispersed in a water-compatible organic solvent and which has a degree of dispersion such that the average particle size of the apatite particles is 1 .mu.m or less and particles of 3 .mu.m or more are practically absent, and a method of manufacture therefor.
2. Description of the Prior Art
Apatites are well-known substances which are widely distributed in the form of phosphate ores, animal bones, etc., but recently the use of apatites has broadened to include materials for artificial bones, materials for dental repair, ion exchangers, etc. Their affinity with living tissue coupled with their environmentally friendly properties promises that they will make their way into yet other fields.
However, in apatites such as hydroxyapatite, even though the primary particles formed during manufacture ire fine particles of 1 .mu.m or less, they tend to aggregate due to Van der Waals forces, ionic charge, etc., and form aggregates of 1 .mu.m or more, especially around 10 to 100 .mu.m.
Consequently, they suffer from the problem that they cannot be used in areas requiring apatites with submicron particle sizes such as anti-blocking agents for films, etc., cosmetics, or UV blocking agents, for example, and their use cannot yet be extended to these areas.
Now, various methods have conventionally been tried which aim to overcome these problems. For example, there is a method (Japanese Patent Laid-Open No. 4-317404) in which the surface of the apatite is reformed and dried after completion of the reaction by adding a fatty acid such as stearic acid. Use of aqueous hydroxyapatite slurry as a stabilizer for suspension polymerization is also well known, and such methods as ultrasonic treatment (Japanese Patent Publication No. 47-38631) and intensive shearing treatment with homogenizers, etc., (Japanese Patents Laid-Open Nos. 7-102005 and 7-102006) have been proposed to disperse the apatite slurry.